Wed, 09/04/2024 - 16:41
The list of standard stars gives the RA & Dec as real numbers. I am only familiar with RA & Dec given as Hours Minutes and Seconds. Can someone please explain to me how to interpret the RA & Dec and given in the list of standard stars?
List of standard stars found here - https://apps.aavso.org/avspec/standardstars
Thanks
Steve - HSTG
I can make sense of the Dec real number but still haven't a clue about how to interpret the Right Ascension number.
Steve - HSTG
I am guessing RA refers to the Ecliptic Longitude (J2000).
Though by no mean am I certain.
Steve - HSTG
J2000 RA in 0-360 degree format
Not ecliptic longitude. That coordinate system has the ecliptic as the fundamental plane and normal to the N ecliptic pole. Right Ascension (RA) is referenced to the celestial equator. So, ecliptic longitude is measured along the ecliptic and RA along the celestial equator.
Not ecliptic longitude. That coordinate system has the ecliptic as the fundamental plane and normal to the N ecliptic pole. Right Ascension (RA) is referenced to the celestial equator. So, ecliptic longitude is measured along the ecliptic and RA along the celestial equator.
Translate "miu Her" given as 266.6146945 to 17 hours, 46 minutes and 03 seconds?
Thanks
Steve
If you meant Mu Her, its J2000 RA is 17 46 27.54 (from Simbad) and that is what I get converting from 266.6146945.
Thank you Ed and Scott for your help!
Note : The name given for Mu Her is :miu Her
That had me scratching my head also.
Steve
First comment: How stupid to list RA and Dec without units.
Example: bet Gem RA = 116.32896 degrees. The units are degrees, but we usually work with hours.
degrees * 0.0667 = hours as a decimal . (I am fairly sure of the 0.0667 conversion factor, but not certain, this might be the cause of slight differences in Simbad and my figures for J2000). But you get the idea....
Hours: 116.32896 degrees * 0.0667 = 7.759141632 hours and hours become 7
Minutes: 0.759141632 * 60 = 45.54849792 minutes become 45
Seconds 0.54849792 * 60 = 32.91 (rounded)
bet Gem RA = 7H:45m:32.91s
As Dec is already in degrees, the "28" is correct and you go through the minuteand second calculations are shown above.
Note that the J2000 values in Simbad are slightly different than the RA calculated here, as noted above..
Ed
PS: Better to look up the current RA and Dec rather than trust this table. Its easy in Simbad
simbad.cds.unistra.fr/simbad/
The multiplicative factor 0.0067 is in fact 1/15 = 0.0666666.... endlessy repeating. Better I say to simply divide RA degrees by 15 to get RA hours (i.e. there are 15 degrees in an hour of RA since 360/24 = 15).
I agree, Scott.
Ed
Two questions:
1. Can I subscribe to a daily digest of posts rather than receiving each one? (If there is I haven't figured it out!)
2. Is there a way to contact the forum admins directly, i.e., other than using the 'email' link they provide, which sends me to Outlook which I don't use?
Thanks,
Chris
PS Apologies for the off-topic post.
The answer to…
Hi Chris,
The answer to your first question is a qualified "yes!" We have just updated our forum software; if you visit forums.aavso.org, you can see the new forums, which some people have already started to use. We'll make the transition official on September 12, one week from now. The new software has options for daily digests:
Discourse Help - How to Configure Activity Summary Emails
As for contacting the forum admins: They can be reached by sending an email to aavso@aavso.org.
(Pro tip from another Microsoft Windows user: If you hover your mouse over the 'email' link without clicking and look at the bottom left corner of your browser window, it should show you the email address inside the link, allowing you to circumvent the irritating "open in Outlook" default behavior.)
I hope this helps!